200 hp 1976 Johnson getting air in fuel line please help!!!!!

Hello everyone I'm new here I recently purchased a 1973 dusky 20ft with a 1976 200 hp Johnson I've replaced the rectifier , water/fuel separator fuel pick up in the tank and hoses from pick up all the way to the engine and carbs,just rebuilt Carbs and replaced fuel pumps and thermostats now here's the problem I put a clear in line fuel filter to watch the fuel level placed it after the primer bulb when the boats is out the water I can rev it all the wAy to 7000 rpm with no miss fire but in the water it seems to lose power till it dies then hard to start and when flushing the motor at home the clear filter will go dry with no fuel what's so ever till she dies what could be making it do this also replaced all six spark plugs if any1 has any idea what could be making it suck air please respond back need serious help

Re: 200 hp 1976 Johnson getting air in fuel line please help!!!!!

Ahoy, Dusky.

Welcome to iboats.

When that happened to me the fuel pickup line had fallen off the connector inside the tank. Worth checking out.

Good luck.

Re: 200 hp 1976 Johnson getting air in fuel line please help!!!!!

Also check the fuel line, i had some pin holes in mine that needed to be fixed. I know it is obvious but you never know.

T

Re: 200 hp 1976 Johnson getting air in fuel line please help!!!!!

Surely a rare and highly valued engine! A couple of things to check. If you have an air leak in the fuel system, the pumps can run out of fuel. Pressurize the fuel system by squeezing the fuel hose bulb. Watch for any fuel leaking/seeping from any connection. If fuel can leak out, air will leak in-not good. Tighten all hose clamps, etc. I'd suggest you get rid of the metal hose barb connection in the lower cowling. Take it out completely. Remove the hose connection on the engine end of the fuel hose. Run the fuel hose thru that new hole in the lower cowling and clamp the end directly to the hose barb on the fuel pump. You need to be using only 3/8" hose line on that engine. Pull the anti-siphon valve out off the top of the tank. Not unusual for grit to lodge by that ball and cause fuel delivery problems-check the action on that ball and blow it out with carb cleaner. Not unusual for the ball valves to go bad inside the fuel hose bulb. Try another fuel hose. I wouldn't rev that engine over 1800 rpm when it's on the trailer. That's a dangerous practice-and could be fatal to the internal rotating assemblies. Only rev it to high rpm's when the engine is under load.